openvswitch: Add packet truncation support.

The patch adds a new OVS action, OVS_ACTION_ATTR_TRUNC, in order to
truncate packets. A 'max_len' is added for setting up the maximum
packet size, and a 'cutlen' field is to record the number of bytes
to trim the packet when the packet is outputting to a port, or when
the packet is sent to userspace.

Signed-off-by: William Tu <u9012063@gmail.com>
Cc: Pravin Shelar <pshelar@nicira.com>
Acked-by: Pravin B Shelar <pshelar@ovn.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index bb0d515b765458d8a8fa6442fce6c5aab6a0aad5..8274675ba9a32eb338dc92872b94fab6617a9c46 100644 (file)
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -580,6 +580,10 @@ enum ovs_userspace_attr {
 
 #define OVS_USERSPACE_ATTR_MAX (__OVS_USERSPACE_ATTR_MAX - 1)
 
+struct ovs_action_trunc {
+       uint32_t max_len; /* Max packet size in bytes. */
+};
+
 /**
  * struct ovs_action_push_mpls - %OVS_ACTION_ATTR_PUSH_MPLS action argument.
  * @mpls_lse: MPLS label stack entry to push.
@@ -703,6 +707,7 @@ enum ovs_nat_attr {
  * enum ovs_action_attr - Action types.
  *
  * @OVS_ACTION_ATTR_OUTPUT: Output packet to port.
+ * @OVS_ACTION_ATTR_TRUNC: Output packet to port with truncated packet size.
  * @OVS_ACTION_ATTR_USERSPACE: Send packet to userspace according to nested
  * %OVS_USERSPACE_ATTR_* attributes.
  * @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header.  The
@@ -756,6 +761,7 @@ enum ovs_action_attr {
                                       * The data must be zero for the unmasked
                                       * bits. */
        OVS_ACTION_ATTR_CT,           /* Nested OVS_CT_ATTR_* . */
+       OVS_ACTION_ATTR_TRUNC,        /* u32 struct ovs_action_trunc. */
 
        __OVS_ACTION_ATTR_MAX,        /* Nothing past this will be accepted
                                       * from userspace. */

diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 9a3eb7a0ebf4bde84f1f323aac88ca0cbc8a8f80..1ecbd7715f6d973d1dd60b33791482949aa3a589 100644 (file)
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -750,6 +750,14 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
 
        if (likely(vport)) {
                u16 mru = OVS_CB(skb)->mru;
+               u32 cutlen = OVS_CB(skb)->cutlen;
+
+               if (unlikely(cutlen > 0)) {
+                       if (skb->len - cutlen > ETH_HLEN)
+                               pskb_trim(skb, skb->len - cutlen);
+                       else
+                               pskb_trim(skb, ETH_HLEN);
+               }
 
                if (likely(!mru || (skb->len <= mru + ETH_HLEN))) {
                        ovs_vport_send(vport, skb);
@@ -775,7 +783,8 @@ static void do_output(struct datapath *dp, struct sk_buff *skb, int out_port,
 
 static int output_userspace(struct datapath *dp, struct sk_buff *skb,
                            struct sw_flow_key *key, const struct nlattr *attr,
-                           const struct nlattr *actions, int actions_len)
+                           const struct nlattr *actions, int actions_len,
+                           uint32_t cutlen)
 {
        struct dp_upcall_info upcall;
        const struct nlattr *a;
@@ -822,7 +831,7 @@ static int output_userspace(struct datapath *dp, struct sk_buff *skb,
                } /* End of switch. */
        }
 
-       return ovs_dp_upcall(dp, skb, key, &upcall);
+       return ovs_dp_upcall(dp, skb, key, &upcall, cutlen);
 }
 
 static int sample(struct datapath *dp, struct sk_buff *skb,
@@ -832,6 +841,7 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
        const struct nlattr *acts_list = NULL;
        const struct nlattr *a;
        int rem;
+       u32 cutlen = 0;
 
        for (a = nla_data(attr), rem = nla_len(attr); rem > 0;
                 a = nla_next(a, &rem)) {
@@ -858,13 +868,24 @@ static int sample(struct datapath *dp, struct sk_buff *skb,
                return 0;
 
        /* The only known usage of sample action is having a single user-space
+        * action, or having a truncate action followed by a single user-space
         * action. Treat this usage as a special case.
         * The output_userspace() should clone the skb to be sent to the
         * user space. This skb will be consumed by its caller.
         */
+       if (unlikely(nla_type(a) == OVS_ACTION_ATTR_TRUNC)) {
+               struct ovs_action_trunc *trunc = nla_data(a);
+
+               if (skb->len > trunc->max_len)
+                       cutlen = skb->len - trunc->max_len;
+
+               a = nla_next(a, &rem);
+       }
+
        if (likely(nla_type(a) == OVS_ACTION_ATTR_USERSPACE &&
                   nla_is_last(a, rem)))
-               return output_userspace(dp, skb, key, a, actions, actions_len);
+               return output_userspace(dp, skb, key, a, actions,
+                                       actions_len, cutlen);
 
        skb = skb_clone(skb, GFP_ATOMIC);
        if (!skb)
@@ -1051,6 +1072,7 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                        if (out_skb)
                                do_output(dp, out_skb, prev_port, key);
 
+                       OVS_CB(skb)->cutlen = 0;
                        prev_port = -1;
                }
 
@@ -1059,8 +1081,18 @@ static int do_execute_actions(struct datapath *dp, struct sk_buff *skb,
                        prev_port = nla_get_u32(a);
                        break;
 
+               case OVS_ACTION_ATTR_TRUNC: {
+                       struct ovs_action_trunc *trunc = nla_data(a);
+
+                       if (skb->len > trunc->max_len)
+                               OVS_CB(skb)->cutlen = skb->len - trunc->max_len;
+                       break;
+               }
+
                case OVS_ACTION_ATTR_USERSPACE:
-                       output_userspace(dp, skb, key, a, attr, len);
+                       output_userspace(dp, skb, key, a, attr,
+                                                    len, OVS_CB(skb)->cutlen);
+                       OVS_CB(skb)->cutlen = 0;
                        break;
 
                case OVS_ACTION_ATTR_HASH:

diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 856bd8dba676418723c420b982af311c140f62fc..6739342953338f7bfaeb6a121cd9ef958c12fc98 100644 (file)
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -137,10 +137,12 @@ EXPORT_SYMBOL_GPL(lockdep_ovsl_is_held);
 static struct vport *new_vport(const struct vport_parms *);
 static int queue_gso_packets(struct datapath *dp, struct sk_buff *,
                             const struct sw_flow_key *,
-                            const struct dp_upcall_info *);
+                            const struct dp_upcall_info *,
+                            uint32_t cutlen);
 static int queue_userspace_packet(struct datapath *dp, struct sk_buff *,
                                  const struct sw_flow_key *,
-                                 const struct dp_upcall_info *);
+                                 const struct dp_upcall_info *,
+                                 uint32_t cutlen);
 
 /* Must be called with rcu_read_lock. */
 static struct datapath *get_dp_rcu(struct net *net, int dp_ifindex)
@@ -275,7 +277,7 @@ void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key)
                upcall.cmd = OVS_PACKET_CMD_MISS;
                upcall.portid = ovs_vport_find_upcall_portid(p, skb);
                upcall.mru = OVS_CB(skb)->mru;
-               error = ovs_dp_upcall(dp, skb, key, &upcall);
+               error = ovs_dp_upcall(dp, skb, key, &upcall, 0);
                if (unlikely(error))
                        kfree_skb(skb);
                else
@@ -300,7 +302,8 @@ out:
 
 int ovs_dp_upcall(struct datapath *dp, struct sk_buff *skb,
                  const struct sw_flow_key *key,
-                 const struct dp_upcall_info *upcall_info)
+                 const struct dp_upcall_info *upcall_info,
+                 uint32_t cutlen)
 {
        struct dp_stats_percpu *stats;
        int err;
@@ -311,9 +314,9 @@ int ovs_dp_upcall(struct datapath *dp, struct sk_buff *skb,
        }
 
        if (!skb_is_gso(skb))
-               err = queue_userspace_packet(dp, skb, key, upcall_info);
+               err = queue_userspace_packet(dp, skb, key, upcall_info, cutlen);
        else
-               err = queue_gso_packets(dp, skb, key, upcall_info);
+               err = queue_gso_packets(dp, skb, key, upcall_info, cutlen);
        if (err)
                goto err;
 
@@ -331,7 +334,8 @@ err:
 
 static int queue_gso_packets(struct datapath *dp, struct sk_buff *skb,
                             const struct sw_flow_key *key,
-                            const struct dp_upcall_info *upcall_info)
+                            const struct dp_upcall_info *upcall_info,
+                                uint32_t cutlen)
 {
        unsigned short gso_type = skb_shinfo(skb)->gso_type;
        struct sw_flow_key later_key;
@@ -360,7 +364,7 @@ static int queue_gso_packets(struct datapath *dp, struct sk_buff *skb,
                if (gso_type & SKB_GSO_UDP && skb != segs)
                        key = &later_key;
 
-               err = queue_userspace_packet(dp, skb, key, upcall_info);
+               err = queue_userspace_packet(dp, skb, key, upcall_info, cutlen);
                if (err)
                        break;
 
@@ -416,7 +420,8 @@ static void pad_packet(struct datapath *dp, struct sk_buff *skb)
 
 static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
                                  const struct sw_flow_key *key,
-                                 const struct dp_upcall_info *upcall_info)
+                                 const struct dp_upcall_info *upcall_info,
+                                 uint32_t cutlen)
 {
        struct ovs_header *upcall;
        struct sk_buff *nskb = NULL;
@@ -461,7 +466,7 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
        else
                hlen = skb->len;
 
-       len = upcall_msg_size(upcall_info, hlen);
+       len = upcall_msg_size(upcall_info, hlen - cutlen);
        user_skb = genlmsg_new(len, GFP_ATOMIC);
        if (!user_skb) {
                err = -ENOMEM;
@@ -515,9 +520,9 @@ static int queue_userspace_packet(struct datapath *dp, struct sk_buff *skb,
                err = -ENOBUFS;
                goto out;
        }
-       nla->nla_len = nla_attr_size(skb->len);
+       nla->nla_len = nla_attr_size(skb->len - cutlen);
 
-       err = skb_zerocopy(user_skb, skb, skb->len, hlen);
+       err = skb_zerocopy(user_skb, skb, skb->len - cutlen, hlen);
        if (err)
                goto out;
 

diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index 427e39a045cf2d98aff3add0b4a9f47c50c467f4..ab85c1cae255b8fd373a0d5e0e1d05841b5bd8d0 100644 (file)
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -100,11 +100,13 @@ struct datapath {
  * @input_vport: The original vport packet came in on. This value is cached
  * when a packet is received by OVS.
  * @mru: The maximum received fragement size; 0 if the packet is not
+ * @cutlen: The number of bytes from the packet end to be removed.
  * fragmented.
  */
 struct ovs_skb_cb {
        struct vport            *input_vport;
        u16                     mru;
+       u32                     cutlen;
 };
 #define OVS_CB(skb) ((struct ovs_skb_cb *)(skb)->cb)
 
@@ -194,7 +196,8 @@ extern struct genl_family dp_vport_genl_family;
 void ovs_dp_process_packet(struct sk_buff *skb, struct sw_flow_key *key);
 void ovs_dp_detach_port(struct vport *);
 int ovs_dp_upcall(struct datapath *, struct sk_buff *,
-                 const struct sw_flow_key *, const struct dp_upcall_info *);
+                 const struct sw_flow_key *, const struct dp_upcall_info *,
+                 uint32_t cutlen);
 
 const char *ovs_dp_name(const struct datapath *dp);
 struct sk_buff *ovs_vport_cmd_build_info(struct vport *, u32 pid, u32 seq,

diff --git a/net/openvswitch/flow_netlink.c b/net/openvswitch/flow_netlink.c
index 0bb650f4f219933fc8f10d455714d7e9016334fe..c78a6a1476fb327fe0c51151c0c277dfbdbb904c 100644 (file)
--- a/net/openvswitch/flow_netlink.c
+++ b/net/openvswitch/flow_netlink.c
@@ -2229,6 +2229,7 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
                        [OVS_ACTION_ATTR_SAMPLE] = (u32)-1,
                        [OVS_ACTION_ATTR_HASH] = sizeof(struct ovs_action_hash),
                        [OVS_ACTION_ATTR_CT] = (u32)-1,
+                       [OVS_ACTION_ATTR_TRUNC] = sizeof(struct ovs_action_trunc),
                };
                const struct ovs_action_push_vlan *vlan;
                int type = nla_type(a);
@@ -2255,6 +2256,14 @@ static int __ovs_nla_copy_actions(struct net *net, const struct nlattr *attr,
                                return -EINVAL;
                        break;
 
+               case OVS_ACTION_ATTR_TRUNC: {
+                       const struct ovs_action_trunc *trunc = nla_data(a);
+
+                       if (trunc->max_len < ETH_HLEN)
+                               return -EINVAL;
+                       break;
+               }
+
                case OVS_ACTION_ATTR_HASH: {
                        const struct ovs_action_hash *act_hash = nla_data(a);
 

diff --git a/net/openvswitch/vport.c b/net/openvswitch/vport.c
index 31cbc8c5c7db821e69945957f346fc361a07f9a0..6b21fd068d874f35c731e6424a1c7560c0038541 100644 (file)
--- a/net/openvswitch/vport.c
+++ b/net/openvswitch/vport.c
@@ -444,6 +444,7 @@ int ovs_vport_receive(struct vport *vport, struct sk_buff *skb,
 
        OVS_CB(skb)->input_vport = vport;
        OVS_CB(skb)->mru = 0;
+       OVS_CB(skb)->cutlen = 0;
        if (unlikely(dev_net(skb->dev) != ovs_dp_get_net(vport->dp))) {
                u32 mark;